Question 1206575
<pre>
of the number of labour cards issued to some artisans by obuasi labour office, 1/3 were issued to carpenters, 1/3 of what remained to drivers, 1/4 of what still remained to masons and the reminder, being 15 to welders. how many masons were issued with labour cards by the office?

{{{1/4}}} of what STILL remained, was issued to masons, so {{{matrix(1,4, 1 - (1/4), ",", or, 3/4)}}} of what STILL remained was
issued to welders. This {{{3/4}}} so happens to be 15 cards. With M being the amount issued to masons, 
we get the following PROPORTION:  {{{matrix(1,3, (3/4)/(1/4), "=", 15/M)}}}
                            {{{matrix(3,3, (3/4)(4/1), "=", 15/M, (3/cross(4))(cross(4)/1), "=", 15/M, 3/1, "=", 15/M)}}}
                                     3M = 15 ----- Cross-multiplying
Number of cards issued to masons, or {{{highlight_green(matrix(1,5, M, "=", 15/3, "=", highlight(5)))}}}</pre>